1. Field
The present invention relates generally to wireless communications, and more specifically to selective content protection.
2. Background
The field of communications has many applications including, e.g., paging, wireless local loops, Internet telephony, and satellite communication systems. An exemplary application is a cellular telephone system for mobile subscribers. (As used herein, the term “cellular” system encompasses both cellular and personal communications services (PCS) system frequencies.) Modern communication systems, such as a wireless communication system, designed to allow multiple users to access a common communications medium have been developed for such cellular systems. These modern communication systems may be based on multiple access techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), space division multiple access (SDMA), polarization division multiple access (PDMA), or other modulation techniques known in the art. These modulation techniques demodulate signals received from multiple users of a communication system, thereby enabling an increase in the capacity of the communication system. In connection therewith, various wireless communication systems have been established including, e.g., Advanced Mobile Phone Service (AMPS), Global System for Mobile communication (GSM), and other wireless systems.
In FDMA systems, the total frequency spectrum is divided into a number of smaller sub-bands and each user is given its own sub-band to access the communication medium. Alternatively, in TDMA systems, the total frequency spectrum is divided into a number of smaller sub-bands, each sub-band is shared among a number of users, and each user is allowed to transmit in predetermined time slots using that sub-band. A CDMA system provides potential advantages over other types of systems, including increased system capacity. In CDMA systems, each user is given the entire frequency spectrum for all of the time, but distinguishes its transmission through the use of a unique code.
A CDMA system may be designed to support one or more CDMA standards such as (1) the “TIA/EIA-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” (the IS-95 standard), (2) the standard offered by a consortium named “3rd Generation Partnership Project” (3GPP) and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the W-CDMA standard), and (3) the standard offered by a consortium named “3rd Generation Partnership Project 2” (3GPP2) and embodied in “TR-45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems” (the IS-2000 standard).
In the above named CDMA communication systems and standards, the available spectrum is shared simultaneously among a number of users, and suitable techniques are available to provide services, such as voice and data services.
Typical mobile subscribers use a mobile station or terminal such as a mobile phone or a laptop to access the wireless communication system. In addition to voice communications, a mobile station may access other network data services, such as Instant Messaging Service (IMS), provisioned by a home 3G system.
A mobile station may have access to a Wireless Local Access Network (WLAN) which could provide an alternative communications channel for accessing network data services provisioned by the home 3G system, without using the home 3G system's “cellular” capacity. FIG. 1 shows the 3G-WLAN interworking architecture. The Mobile Station (MS), via a Wireless Local Area Network (WLAN) system, can access services in MS's home network. The Packet Data Interworking Function (PDIF) acts as a secure gateway guarding the network services (e.g., Instant Messaging Service (IMS)) against unauthorized access. IMS is a SIP-based system that allows the MS to setup Voice over Internet Protocol (VoIP) calls.
In order to access the IMS service from a WLAN system, the MS uses Internet Key Encryption version 2 (IKEv2) to establish a secure IP tunnel with the Packet Data Interworking Function (PDIF). The tunnel establishment is authenticated and authorized by the Home Authentication Authorization Accounting (H-AAA). The dashed line is the path for Authentication, Authorization, Accounting (AAA) information. The solid lines are the bearer path for user data traffic, and the pipe is the secure IP tunnel protecting the user data traffic between the MS and PDIF. After the secure IP tunnel is established, the MS can register with the IMS in the 3G home network. The Session Initiation Protocol (SIP) is used for the MS to communicate with the control entities (e.g., Proxy-Call Session Control Function (P-CSCF)) in the IMS.
However, the secure IP tunnel is inefficient for particular types of traffic. There is therefore a need in the art for a mobile station and 3G network configured to permit the mobile station to efficiently access network data services provisioned by the 3G system, without using the 3G system's “cellular” capacity.